Abstract

Treatment of chronic pain conditions such as fibromyalgia is challenging due to limitations
of drug therapies. An initial exploration into the relationships between self-reported
alcohol consumption, symptom severity, and quality of life for individuals with fibromyalgia
sheds new light on plausible hypotheses and potential mechanisms of action for future
research. Evidence suggests that alcohol consumption may improve social and psychological
factors because of activity in the ascending and descending pain pathways in modulating
gamma-aminobutyric acid neurotransmission. Further methodologically rigorous studies
in this field to improve well-being of individuals with fibromyalgia are warranted.

Editorial

In a previous issue of Arthritis Research & Therapy, Kim and colleagues [1] reported the first study to examine the association between alcohol consumption,
symptom severity, and quality of life of individuals with fibromyalgia (FM). Treatment
of chronic pain conditions such as FM is challenging because the drug therapies currently
available are expensive and associated with numerous limitations such as undesirable
side effects and addiction or tolerance issues. Despite undergoing drug treatment,
patients are often left with unrelieved pain, restricted mobility, and reduced physical
function. Lifestyle interventions, including dietary modifications such as alcohol
consumption, have gained popularity as explorations in symptom management.

Several observational studies have examined the association between alcohol consumption
and chronic pain conditions. In a prospective study, Bergman and colleagues [2] found that regular weekly or daily alcohol consumption is a significant protective
factor for the development of chronic pain. Two case–control studies have also shown
that moderate alcohol consumption correlates with a reduced risk of rheumatoid arthritis
[3,4]. However, a systematic review of nine epidemiological studies has concluded that
alcohol consumption is not associated with low back pain [5]. Kim and colleagues are the first to examine the association between alcohol consumption
and FM symptom severity and quality of life. Among the 946 adult FM patients (94 %
women, mean age of 49 years old) reporting low or moderate alcohol consumption (≤3
or >3 to 7 drinks per week), there was lower FM symptom severity and better quality-of-life
scores compared with those who reported no alcohol consumption (non-drinkers). However,
these associations were not observed in patients who were heavy drinkers (>7 drinks
per week) compared with non-drinkers. Drinkers had higher education, less unemployment,
lower body mass index, and lower frequency of opioid use than non-drinkers. Thus,
their analyses were adjusted for these potential confounders.

Because alcohol consumption consists of complex behaviors that intersect with many
social, economic, psychological, and demographic factors, disentangling this complex
web of relationships is a challenge. Interestingly, after exploring possible mechanisms
for their findings, Kim and colleagues speculated that alcohol consumption may attenuate
FM symptoms and improve quality of life by mediating psychological benefits and stress
relief or by promoting factors associated with social integration. Another possible
mechanism proposed is central nervous mediation via the modulating gamma-aminobutyric
acid (GABA) system. Several neurotransmitters (including GABA) in the ascending and
descending pain pathways have been implicated in FM [6]. Thus, behavioral and pharmacological therapies that modulate or mimic the effects
of GABA production can be promising for FM treatment.

This initial exploration into the relationships between alcohol consumption, symptom
severity, and quality of life for FM has posed a number of questions that need to
be answered by future studies with stronger study designs. Kim and colleagues discussed
limitations associated with cross-sectional study design, and we would like to underscore
additional concerns relating to the potential for non-random misclassifications of
alcohol consumption among FM patients with different levels of symptom severity or
quality of life. Such information bias is not uncommon in cross-sectional studies
providing data on both exposure and outcome variables from questionnaires. Because
the questionnaires are administered at the same time in a cross-sectional study and
relied on respondent recall, the measurement errors of exposure (that is, alcohol
consumption) may be dependent on the measurement errors of the outcomes (that is,
quality of life or FM symptoms). If such dependent bias occurs, the observed association
between exposure and outcome is likely to be inflated [7]. Owing to lack of prior data demonstrating that such bias exists in cross-sectional
studies of alcohol consumption and FM symptom severity, we provide a possible scenario
to examine the potential impacts of dependent bias on this relationship. FM patients
who on one occasion had more severe symptoms may in fact have consumed more alcohol
to ameliorate symptoms and thus may have felt better (fewer symptoms) at the time
of the survey, or FM patients with more severe symptoms at the time of the survey
may have stopped drinking alcohol (thus no symptom relief) because of their symptoms.
The impact of such dependent bias would result in an inflation of the ‘true’ association.
Owing to cross-sectional design, this potential bias cannot be evaluated. In addition
to the potential for dependent bias, patients with FM may be too embarrassed to reveal
their ‘true’ alcohol intake level because of social desirability biases [8]. Such reporting bias [9], however, is likely to be random and independent of symptom severity. There is still
great uncertainty in the study results; therefore, we agree with Kim and colleagues
that these preliminary results should not be used as grounds for advising patients
to drink alcohol.

In sum, the study by Kim and colleagues sheds new light on plausible hypotheses and
mechanisms to consider in future methodologically rigorous studies to improve the
well-being of individuals with FM. Because it may not be feasible to randomize alcohol
consumption in human subject research, methodologically rigorous prospective longitudinal
studies are needed. Measuring alcohol consumption at different time points is essential
in order to minimize dependent biases from patient-reported exposure and outcome measures.

Abbreviations

FM: Fibromyalgia; GABA: Gamma-aminobutyric acid.

Competing interests

The authors declare that they have no competing interests.

Acknowledgments

CW is supported by awards from the National Center for Complementary and Alternative
Medicine. The contents of this editorial are solely the responsibility of the authors
and do not necessarily represent the official views of the National Center for Complementary
and Alternative Medicine or the National Institutes of Health. The sponsors had no
role in the design and conduct of the study; collection, management, analysis, and
interpretation of the data; or preparation, review, or approval of the editorial.